In prosthodontic procedures designed to implant a dental prosthesis in the intra oral cavity, the dental site at which the prosthesis is to be implanted in many cases needs to be measured accurately and studied carefully, so that a prosthesis such as a crown or bridge, for example, can be properly designed and dimensioned to fit in place. A good fit is of the highest importance to enable mechanical stresses to be properly transmitted between the prosthesis and the jaw, and to prevent infection of the gums and so on via the interface between the prosthesis and the dental site, for example.
In the prior art, the dental site is prepared by the dental practitioner, and a positive physical model of the site is constructed using known methods. Alternatively, the dental site may be scanned to provide 3D data of the site. In either case, the virtual or real model of the site is sent to the dental lab, which manufactures the prosthesis based on the model. However, if the model is deficient or undefined in certain areas, or if the preparation was not optimally configured for receiving the prosthesis, the dental technician has a more difficult job ahead than otherwise, and the design of the prosthesis may be less than optimal. For example, if the insertion path implied by the preparation for a closely-fitting coping would result in the prosthesis colliding with adjacent teeth, the coping geometry has to be altered to avoid the collision, but this may result in the coping design being less optimal. Further, if the area of the preparation containing the finish line lacks definition, it may not be possible to properly determine the finish line an thus the lower edge of the coping may not be properly designed. Indeed, in some circumstances, the model is rejected and the dental practitioner must re-scan the dental site, or must rework the preparation, so that a suitable prosthesis may be produced.
In orthodontic procedures it is also necessary to provide a model of one or both jaws. Where such orthodontic procedures are designed virtually (herein also referred to as “numerically”), a virtual model of the intraoral cavity is also required, and this may be obtained, inter alia, by scanning the intraoral cavity directly, or by producing a physical model of the dentition, and then scanning the model with a suitable scanner.
Thus, in both prosthodontic and orthodontic procedures, obtaining a three-dimensional (3D) model of a least a part of the intraoral cavity is an initial requirement. When the 3D model is a virtual model, the more complete and accurate the scans of the intraoral cavity are, the higher the quality of the virtual model, and thus the greater the ability to design an optimal prosthesis or orthodontic treatment.
Prior art methods of scanning the intraoral cavity do not provide guidance to the dental practitioner on how to ensure full and accurate scanning of parts of the cavity of interest for a particular orthodontic or prosthodontic procedure. Rather, the dental practitioner uses his or her judgment on site, and it is often the case that the scans of some areas of interest may be defective, while other unimportant areas may be scanned to great accuracy with details, which is wasteful of the practitioner's and the patient's time.